1. Technical Field of the Invention
The present invention relates to a method of constructing a composite material capable of acting as a nanoadhesive. More specifically, the present invention relates to a method of constructing a composite material having nanofibers exposed therefrom, which provide the desired nanoadhesive properties.
2. Background of the Invention
Geckos possess a unique ability that allows them to climb vertical walls and horizontal surfaces, such as ceilings, with relative ease. Their feet, or toe pads, contain high aspect ratio beta-keratin structures that adhere to any surface with a pressure controlled contact area. As shown by Metin Sitti and Ronald S. Fearing (M. Sitti and R. Fearing, “Synthetic Gecko Foot-hair Micro/nano-structures as Dry Adhesives”, J. Adhesion Sci. Technol., Vol. 17, No. 8, pp. 1055-1073 (2003)), each foot of a gecko contains millions of these high aspect ratio structures called spatula stalks, which in turn have spatulae at their ends. These spatulae, in combination with each other, provide the necessary force to support the gecko as it traverses walls, ceilings and other objects. What is more impressive though is that these same spatulae allow for a quick release, allowing the gecko to move so quickly and fluidly across walls and ceilings. The spatula stalks are approximately 100-200 nm in diameter, with the spatulae having approximately 300-500 nm width at their ends. Sitti and Fearing focused their research on producing these hair-like structures using nano imprinting. In this method, they started out with a wax and poked it with a probe to produce an indented surface. A polymer was then used to create a mold of the indentions, and then the polymer and wax were separated from each other, leaving a polymer mold having high aspect ratio protrusions. However, this method does not allow for the growing of nanofibers on a flexible substrate. Furthermore, nano imprinting has problems related to overlay, defects, template patterning and template wear. Additionally, there are proximity effects associated with imprinting that cause the outer layers of the imprint to fill more quickly than the middle sections leaving an uneven imprint.
Therefore, it would be beneficial to have a method of producing a composite material that could act as a nanoadhesive and was able to be constructed on a flexible substrate, and using a variety of starting materials.